This invention relates to a compressor, and more particularly to a compressor having a mechanism which makes it suitable to use as an air compressor for vehicles in which the discharging pressure thereof is obtained by delivering under pressure a gaseous working fluid.
Conventional compressors are constituted in such a manner that, for example as disclosed in FIG. 1 of Japanese Patent Laid-Open No. 61-237887, a cylinder block, a wobble plate and pistons rotatably supported by the wobble plate are rotated, through a pair of bevel gears, around the axes of the shafts inclined relative to each other, and the rotation of these elements is caused in synchronization with each other. As a result of the substantial swinging or wobbling movement of the wobble plate, the pistons are reciprocated within the through holes or the cylinder bores so that a suction, compression, and discharge processes may be conducted. The bevel gears serve as a mechanism for transmitting a torque between the inclined shafts.
However the bevel gears employed in the prior art as the mechanism for transmitting torque between the inclined shafts are desired to be eliminated, since they may generate a noise due to its backlash, impair reliability of the product and give uncomfortable feeling to users. Furthermore, the prior art is constructed such that each of the driving shaft and the driven shaft is supported in a cantilever fashion through a single bearing, and that centering between the two shafts is effected through a ball disposed at the central portion of the bevel gears engaging with each other. With such construction, since not only the thrust force (force in the axial direction) but also the radial force are applied to the shafts, the shafts are caused to be oscillated, and hence uneven wear of the spherical bearing portion including the ball as well as the uneven wear and vibration of the bevel gears would occur. As a result, noise generation cannot be prevented.
Furthermore, in the case where the capacity of the compressor is intended to be controlled, since the inclination angle of the rotation center axis of the wobble plate cannot be varied, the refrigerant having been sucked in the cylinder bore has to be returned to the passage of low pressure side during the compression process so as to control the amount of the discharged gas. Therefore, problems arise in that the temperatures of the sucked gas and the discharged gas are raised, and hence the volumetric efficiency and the mechanical efficiency are deteriorated.
A compressor of cylinder rotating type similar to that disclosed in Japanese Patent Laid-Open No. 61-237887 is disclosed in U.S. Pat. No. 4,644,850. Also U.S. Pat. Nos. 3,656,299, and 4,283,997 disclose similar arts. However, the structure disclosed in these U.S. Patents are substantially identical with the above-described prior art structure in the mechanism for rotating the wobble plate.